Silvio Berlusconi is tomorrow facing the biggest threat yet of his tumultuous career, as prosecutors ask for him to stand trial for sex-related offences that carry a combined sentence of up to 15 years. It was also announced today that his trial for allegedly bribing British lawyer David Mills is to resume on 11 March.

The media tycoon-turned-politician will take another blow tomorrow when six private videos filmed at his homes in Rome and Sardinia are covered in the weekly magazine Oggi; they reportedly feature Noemi Letizia, the teenager whose still-unexplained relationship with Berlusconi set off the string of recent scandals involving Italy's prime minister.

Last month it emerged that Berlusconi had been formally put under investigation in Milan suspected of paying an underage prostitute and then trying to cover up the fact by abusing his authority, both being criminal offences if proven.

But while many believe the indictment request could mark the beginning of the end of Berlusconi, few are ready to predict the timing.

Italo Bocchino, among several parliamentarians who broke with him last July, told the Guardian: "When people ask me when the Berlusconi era will come to an end, I answer: 'In two days, two months or two years'."

There has been no sign of rebellion, or even protest, from inside Berlusconi's Freedom People movement. And two opposition attempts to remove him last year failed.

Though his personal rating has been eroded, voting intentions for his party remain solid. A survey by the weekly Famiglia Cristiana showed only half of observant Roman Catholics were critical of his behaviour.

Berlusconi is meeting lawyers and the justice minister in Rome after learning of decisions by the investigating prosecutors to ask a judge to put him in the dock as early as Easter. Following a meeting of those directly involved in the investigation, it was reported that they intend to ask for Berlusconi to be indicted alone, charged with the two offences.

The chief prosecutor of Milan had earlier made clear that his department had opted for a fast-track procedure which dispenses with the need for a pre-trial hearing; three close associates of Berlusconi have also been made suspects, but indicting them too would complicate the case and might slow it down.

The prime minister denies any wrongdoing, and several aspects of his defence case have been endorsed by the woman in question — Karima el-Mahroug, a runaway-turned-nightclub dancer also known as Ruby Rubacuori, or Ruby the Heartstealer. Last May she was arrested on suspicion of theft and taken to a Milan police station. But instead of being returned to care, she was handed over to a friend of the prime minister after Berlusconi spoke by phone to a senior police official.

According to leaks from the subsequent investigation, the friend found her a home with a Brazilian woman alleged to be a prostitute. The investigation uncovered evidence, which Berlusconi's lawyers dispute, that el-Mahroug had several times visited the prime minister's home near Milan. The prosecutors maintain that, at the time in question, she was 17 years old. But according to a report in Il Giornale, a newspaper owned by the Berlusconi family, the prime minister's lawyers have evidence that she was in fact 18 at the time in question.

Documents submitted to parliament last month contained witness statements and wiretap transcripts indicating that dinners at the villa were attended by large numbers of women, and led on to striptease and sex play.

Under Italian law the age of consent is 14. But paying for the services of a prostitute aged less than 18 is an offence, punishable by up to three years in prison; to secure a conviction, the prosecution does not have to prove full sexual intercourse.

The judge appointed to oversee the case will have five days in which to decide for or against an indictment. But she can opt to set up a pre-trial hearing to hear the evidence relating to the juvenile prostitution charge before reaching a decision.

Berlusconi's trial for allegedly buying favourable testimony from David Mills was suspended after the introduction of a law, sponsored by his government, which would have enabled him to delay the proceedings until he left office. The law was partially overturned by the constitutional court last year.